Dummy Plugs/ Multiple GPUs

[Chucksta]

I've had EnableUlps set to 0 for quite some time (Crossfire related problem with 1 card randomly going to 0% load).  I can confirm that this will NOT allow you to start mining on a GPU that doesn't have a monitor attached.

My solution.  My monitor has 3 inputs.  I plug my 2 cards in to it.  1 DVI 1 DVI-VGA.  Start mining and overclock 1st card, hit switch input, start mining and overclock 2nd card.

Did you set it up on all cards eg. under the 0000 and 0001 or 0003 keys? It works fine for me, my config:
Windows 7 x86
HIS Radeon 5850
ASUS Radeon 5850 DirectCu TOP
Latest catalyst drivers.
CrossFireX enabled
Cards are linked with CrossfireX bridge. If it still doesn't work, there's another solution, run furmark or another GPU heavy application for a minute, then the second GPU will appear ready for mining - I was doing this before learning the ULPS trick.

This did not work for me either. I had changed all 3 keys to 0, but my cards are not linked by a CrossfireX bridge. I expect the CrossfireX bridge is the key here. If so, then I will stick with a KVM, as crossfire has a detrimental affect on the mining performance.

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[Internet151]

I tried this registry tweak too under Windows 7 32-bit without crossfire on keys 0000 0001 0002 and 0003.

Didn't work.

[namley]

I do something similar but not really.

I'm using Pheonix as my RPC miner, and I do this

Step 1: Start miner on Card 1
  phoenix.exe DEVICE=1
Step 2: Switch VGA/DVI/HDMI cable to Card 2
  Phoenix.exe DEVICE=1
Step 3: Switch VGA/DVI/HDMI cable to Card 3
  Phoenix.exe DEVICE=1

Notice the device number is the same, but it initiates the process thread depending on the Active GPU in windows.

I have only tested this in Windows 7, no other operating system.

Works for me

Hope this helps.

[5tr1k3r]

Cheaper and simpler dummy plug.

http://www.overclock.net/folding-home-guides-tutorials/384733-30-second-dummy-plug.html

Even cheaper and simpler dummy plug:

http://blog.zorinaq.com/?e=11

I'm using 2 of them...

Some more confirmations from somebody else? Looks like good and easy method.

[willphase]

Cheaper and simpler dummy plug.

http://www.overclock.net/folding-home-guides-tutorials/384733-30-second-dummy-plug.html

Even cheaper and simpler dummy plug:

http://blog.zorinaq.com/?e=11

I'm using 2 of them...

Some more confirmations from somebody else? Looks like good and easy method.

I would (personally) avoid this - if the wires cross somehow you're blowing the vid interface rather than your VGA converter.  Use the VGA converter that comes with every video card, and just put the resistor between pins 1 and 6 - you only need one resistor (there is no benefit to 3, just costs 3x as much).

W

[Nemesis099]

Just build a dummy plug, all you need are some resistors and a dvi/vga adapter/port.
I used to do this, but everytime my PC would restart or power went out, it was a bitch doing this every day!

Dummy plugs, no worries!

My linux server has 186days uptime.  Where do you live that power goes out that frequently?

Its not about where I live lol..its my damn apartment circuit at home...1.2 ghash takes alot of power with these damn 5830s..i plug a hair dryer in and blows the circuit..

If that is the case I highly recommend you plug into a different outlet as well as get a battery backup.

I got a battery backup and put mine in the basement where it has a 20Amp breaker and the only other thing hooked up is a freezer.

If you are blowing the circuit breakers all the time I would be worried.

[nazgulnarsil]

Cheaper and simpler dummy plug.

http://www.overclock.net/folding-home-guides-tutorials/384733-30-second-dummy-plug.html

Even cheaper and simpler dummy plug:

http://blog.zorinaq.com/?e=11

I'm using 2 of them...

you the man.

[mjsbuddha]

I dont get how you people get 2 cards running at all without the crossfire cable. I have 5 machines, each with 2 5970's in them. If I try to run them with a dummy plug and without the crossfire cable, they will run for a few minutes then the system will crash and it'll say there was a "Hyper Transport sync flood error" and I have to reinstall the drivers before all 4 cores are recognized again.

[Chucksta]

I dont get how you people get 2 cards running at all without the crossfire cable. I have 5 machines, each with 2 5970's in them. If I try to run them with a dummy plug and without the crossfire cable, they will run for a few minutes then the system will crash and it'll say there was a "Hyper Transport sync flood error" and I have to reinstall the drivers before all 4 cores are recognized again.

I use a KVM and 1 monitor.

Monitor goes into KVM

cables go from KVM into GFX cards of my computers

job done

[kokojie]

if I use linux, I don't need dummy plugs right? just planning hardware right now

[Bitonetta]

if I use linux, I don't need dummy plugs right? just planning hardware right now

Correct.  All mine are headless even.

[Folax]

if I use linux, I don't need dummy plugs right? just planning hardware right now

Correct.  All mine are headless even.

Confirmed. Solved all my issues. Also the hash rates are more stable and less heat: Winning!

[phelix]

OK, I would like to sum up what we know about dummy plugs. It has been bothering me quite a bit. Please correct and extend.

• Linux: no dummy plugs needed
• Win7: it is possible to force activate screens in display properties or change the EnableULPS registry entry
• WinVista: ?
• WinXP: dummy plugs or crossfire needed? did anyone manage to get it to work some other way?

[um0rion]

OK, I would like to sum up what we know about dummy plugs. It has been bothering me quite a bit. Please correct and extend.

• Linux: no dummy plugs needed
• Win7: it is possible to force activate screens in display properties or change the EnableULPS registry entry
• WinVista: ?
• WinXP: dummy plugs or crossfire needed? did anyone manage to get it to work some other way?

Ive got Vista Ultimate running 2x cards, NOT in crossfire, 1 with a monitor hooked to it, and 1 with a dummy plug.

Ive also got Windows XP running 4x 5850s using dummy plugs, no crossfire cables.

[kokojie]

Cheaper and simpler dummy plug.

http://www.overclock.net/folding-home-guides-tutorials/384733-30-second-dummy-plug.html

Even cheaper and simpler dummy plug:

http://blog.zorinaq.com/?e=11

I'm using 2 of them...

Some more confirmations from somebody else? Looks like good and easy method.

I would (personally) avoid this - if the wires cross somehow you're blowing the vid interface rather than your VGA converter.  Use the VGA converter that comes with every video card, and just put the resistor between pins 1 and 6 - you only need one resistor (there is no benefit to 3, just costs 3x as much).

W

a signal from resistor can blow the vid interface or the VGA converter? how does that work exactly?

[keybaud]

Cheaper and simpler dummy plug.

http://www.overclock.net/folding-home-guides-tutorials/384733-30-second-dummy-plug.html

Even cheaper and simpler dummy plug:

http://blog.zorinaq.com/?e=11

I'm using 2 of them...

Some more confirmations from somebody else? Looks like good and easy method.

I would (personally) avoid this - if the wires cross somehow you're blowing the vid interface rather than your VGA converter.  Use the VGA converter that comes with every video card, and just put the resistor between pins 1 and 6 - you only need one resistor (there is no benefit to 3, just costs 3x as much).

W

A standard HDMI port outputs digital in the block connector and standard analogue VGA on the cross connector. All a HDMI to VGA plug does in put the analogue connectors to a VGA pin format.

Analogue VGA outputs a Red, Green and Blue signal, known as RGB. All you need to do is put a resistive shunt across one channel to make Windows think you have a monitor attached.

Putting a resistor across the R, G or B channel (or all 3 if you mistakenly think it will make a difference) has the same affect whether you use the HDMI analogue connectors or the VGA adaptor analogue connectors. If you cross the pins on the HDMI to VGA adaptor it will have EXACTLY THE SAME AFFECT as if you'd crossed them on the HDMI connector.

The only difference using an adaptor has is that it may cost you more money.

[PcChip]

I'm really surprised nobody has mentioned the benefit to NOT using dummy plugs.

I use the swap-monitor trick to get them all going because, for example, my 5830 does 300 MH/s with the monitor plugged in.  When I unplug the monitor to swap over to the 5850, the hashrate goes up to 304 MH/s.

I'm assuming dummy plugs would decrease all hashrates by 1%

[phelix]

I'm really surprised nobody has mentioned the benefit to NOT using dummy plugs.

I use the swap-monitor trick to get them all going because, for example, my 5830 does 300 MH/s with the monitor plugged in.  When I unplug the monitor to swap over to the 5850, the hashrate goes up to 304 MH/s.

I'm assuming dummy plugs would decrease all hashrates by 1%

how did you measure the 1%?

[qed]

OK, I would like to sum up what we know about dummy plugs. It has been bothering me quite a bit. Please correct and extend.

• Linux: no dummy plugs needed

• Win7: it is possible to force activate screens in display properties or change the EnableULPS registry entry

• WinVista: ?
• WinXP: dummy plugs or crossfire needed? did anyone manage to get it to work some other way?

That's 100% false and not working. ULPS is the powersaving feature on cards that are already in CrossfireX therefor active.

[PcChip]

how did you measure the 1%?

I guess I should have just stated the overall hash rate increase,

350 -> 356

300 -> 304

obviously the increase is because the gpu no longer has to render the desktop